U.S. data on incidents from 2005 to 2009 “show that road and rail have higher rates of serious incidents, injuries and fatalities than pipelines, even though more road and rail incidents go unreported,” said the report authors, Manhattan Institute senior fellow Diana Furchtgott-Roth and Kenneth Green, senior director of natural resource policy studies at the Fraser Institute.

“Transporting oil by pipeline is safe and environmentally friendly,” the report concluded.

Pipelines carry the bulk of oil moving across the United States and Canada each day, even though the surge in North American production has pushed more and more crude into trucks and onto trains. Under the current breakdown of crude oil and petroleum product transport In the United States, evaluated on a ton-mile basis:

70 percent is shipped by pipeline

23 percent is moved by tankers and barges

4 percent is shipped via trucks

3 percent moves on rail

Given the breakdown, Furchtgott-Roth and Green acknowledged it would be natural to expect pipelines to be responsible for more spills and injuries. But using data from U.S. and Canada, they found that road transport was the most dangerous option in terms of the number of incidents, with almost 20 for every billion ton-miles. By contrast, there were roughly two incidents per billion ton-miles traveled annually by train. Pipelines had fewer than 0.6 incidents per billion ton-miles annually.

The rates of injuries requiring hospitalization are 30 times lower among oil pipeline workers compared to rail workers involved in crude shipments, according to U.S. data analyzed by the pair. Trucking oil is 37 times more likely to cause such injuries than pipelines, they found.

The researchers say the “superior safety and environmental performance of pipelines is hardly surprising,” since the pipes are often buried underground and less exposed to damage. And there is extra protection in that pipelines allow oil to flow through its shipping container, rather than via containers that are being hauled around.

“When you have more moving parts, more potential interactions with other non-controlled actors such as trains and trucks, the potential for accidents is higher when compared to pipelines,” Green said.

But even though pipeline accidents are less frequent, when they do happen, they generally cause much bigger spills.

Even when pipeline operators react quickly to a leak, they can only close off long segments of pipe — and the high pressure of the fluid flowing through it means plenty can spew out of even small cracks.

Take, for instance, the incident in North Dakota — now believed to be the biggest onshore oil spill in the United States. In that case, an estimated 20,600 barrels of oil — and possibly more — spewed out of a quarter-inch-wide hole in Tesoro Corp.’s 20-year-old pipeline.

Green said the clash between the number of incidents and the size of spills among various forms of oil transportation mean that it is unclear which is the best method in terms of safeguarding the environment:

“When you have a pipeline spill, the release volumes are higher than for a truck or train incident. But with road and rail you have risk of more incidents in more places, so the overall question of environmental protection becomes unclear.”

Such safety issues could loom large in the Obama administration’s decision whether to give a permit for TransCanada Corp. to build its proposed Keystone XL pipeline across the U.S.-Canada border. The State Department is finalizing an environmental assessment of the project, that, as initially drafted, concluded that even if Keystone XL is never built, bitumen harvested from Canada’s oil sands will find its way into the marketplace via trucks and trains.

Shipping via rail generally costs more than moving crude through an aging network of pipelines originally built for yesterday’s oil drilling hotbeds, but train transport offers more flexibility and can more quickly adapt to the surge in production in areas like North Dakota.

That accident has already prompted new regulations in Canada, a potential rule making at the U.S. Department of Transportation, and worry by community leaders along rail lines in the U.S., worried about cargoes of both crude and ethanol rolling by. New scrutiny has been directed at the most commonly used oil tank cars on U.S. and Canadian rails today, which are single-walled designs.

Jennifer A. Dlouhy covers energy policy, politics and other issues for The Houston Chronicle and other Hearst Newspapers from Washington, D.C. Previously, she reported on legal affairs for Congressional Quarterly. She also has worked at The Beaumont Enterprise, The San Antonio Express-News and other newspapers. Jennifer enjoys cooking, gardening and hiking. She lives in Washington, D.C., with her husband and toddler son.

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